Combined analysis of the decays τ- → KSπ- ντ and τ- → K- ηντ

In a combined study of the decay spectra of tau(-) -> KS pi(-) nu(tau) and tau(-) -> K- eta nu(tau) decays within a dispersive representation of the required form factors, we illustrate how the K*(1410) resonance parameters, defined through the pole position in the complex plane, can be extracted with improved precision as compared to previous studies. While we obtain a substantial improvement in the mass, the uncertainty in the width is only slightly reduced, with the findings M-K*/ = 1304 + 17MeV and M-K*/ = 171 + 62 MeV. Further constraints on the width could result from updated analyses of the K71 and/or 1-07 spectra using the full Belle-I data sample. Prospects for Belle-II are also discussed. As the K-70 vector form factor enters the description of the decay tau(-) -> KS pi(-) nu(tau), we are in a position to investigate isospin violations in its parameters like the form factor slopes. In this respect also making available the spectrum of the transition tau(-) -> KS pi(-) nu(tau) would be extremely useful, as it would allow to study those isospin violations with much higher precision.